Variable capacity fuel pump



July 5 1956 R. w. HALBERG ETAL 3,259,076

VARIABLE CAPACITY FUEL PUMP Original Filed Feb. 5, 1960 2 Sheets-Sheet 1 July 5, 1966 R. w. HALBERG ETAI. 3,259,076

VARIABLE CAPACITY FUEL PUMP 2 Sheets-Sheet 2 Original Filed Feb. 5, 1960 United States Patent O 3,259,076 VARIABLE CAPACITY FUEL PUMP Robert W. Halberg, Des Plaines, Abraham L. Detweiler,

Barrington, and Renee W. Danforth, Palatine, Ill., assignors to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Original application Feb. 5, 1960, Ser. No. 6,946. Divided and this application Mar. 10, 1965, Ser. No. 448,225 3 Claims. (Cl. 10S-205) This application is a division of our previous application Serial No. 6,946, filed February 5, 1960, now abandoned.

This invention relates to a fluid pump adapted to provide a variable volume output at a substantially constant pressure.

The pump of the present invention is intended to be used particularly as a primary supply pump for a fuel injection system.

This invention constitutes an improvement to an earlier invention disclosed in the application of Abraham L. Det- Weiler et al., Serial No. 809,807, filed April 19, 1959, now abandoned. Y

The present invention is intended to overcome a major deficiency of earlier pumps of this general type, namely noise. Noise within the pump may be generated because of the in-termittent separation between the driving member and the pumping plunger.

It is an object of the present invention to provide an improved fluid pump comprising a variable stroke plunger and eccentric driving means for reciprocating the plunger so as to develop a substantially constant pressure, variablevolume output.

It is a more particular object to provide resilient means between the driving motor and the pumping plunger eiective to eliminate noise due to intermittent contact between the eccentric and the plunger.

The invention consists of the novel construction, arrangements, and devices to be hereinafter described and claimed for carrying out the above-stated objects and such other objects as will appear from the following description of a preferred form of the invention, illustrated with reference to the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view of the improved pump of the present invention;

FIG. 2 is a view taken along line 2-2 of FIG; l;

FIG. 3 is a view taken on line 3-3 of FIG. 2; andV FIG. 4 is a modification of the pump of FIG. 2 including driving means for a vacuum pump.

Like characters of reference designate like parts in the several views.

Referring to the drawings, the pump of the present invention is designated generally by the numeral 10 and comprises a driving section 11, a pumping section 12, and a vapor separating section 13. Y The driving section 11 comprises an electric drive motor 14 having an output shaft 15, and an eccentric driving shaft or crankshaft 16 connected to the output shaft 15 by means of a resilient coupling 17. The eccentric or crankshaft 16 is journaled within a housing 1S by means of a plurality of bearings 19. The housing 18 is attached to a housing 20 for the electric motor 14 by a plurality of machine screws 21. The eccentric shaft 16 extends into a cavity 22 formed within the housing 1 and carries a sleeve 23 journaled on an end of the eccentric shaft 16 by means of a bearing 24.

It is contemplated that the electric motor 14 may be of a compound type that operates at a substantially constant speed under all conditions while still providing a high starting torque.

The pumping section 12 comprises a casing 30 having a stepped longitudinal cylindrical bore 31 and a pumping plunger 32 reciprocably disposed within the bore 31. The pumping plunger 32 carries a spring retainer 33 xedly -attached to one end thereof by means of a screw 34. The screw 34 carries a rubber cap 35 which contacts the driving sleeve 23 on the eccentric drive shaft 16. A spring 36 is disposed under compression within a recess 37 formed in the housing 30 and acts against the spring retaining cap 33. The spring 36 urges the piston 32 to the left as shown during a portion of the pumping stroke. An anti-backlash spring 38 is also mounted within housing 18 in the cavity 22 and acts against the driving sleeve 23. The spring 38 preferably is formed in a generally U- shaped configuration of a continued strand of spring material and engages the sleeve 23 to urge the sleeve 23 and eccentric shaft 16 to the left, as shown, so as to take up `any backlash or clearance within the bearings 19 and 24.

The pumping plunger 32 is formed with an enlarged cylindrical head 39 which extends into an enlarged portion of the bore 31. The head 39 separates the enlarged portion of the bore 31 into two pumping chambers designated as 31a and 31b. The outer diameter of the cavity 31a is preferably twice the size of that of the bore 31 through which the body of the pumping plunger 32 eX- tends.

The head 39 of the pumping plunger 32 is formed with a stepped cylindrical bore 40 and a longitudinal channel 41 connecting the bore 40 with the chamber 31a. A spring-loaded discharge Valve 42 is disposed within the bore 40 and is retained in place by means of an end cap 43 fixedly `attached to the head 39. The cap 43 is formed with a central port 44 openings into the chamber 31h. An annular leaf spring inlet valve 45 is disposed adjacent the chamber 31b and admits fuel thereto from a fuel inlet conduit 46. The chamber 31a is connected through an outlet port 47 to a fuel feeding device for an internal combustion engine (not shown).

The vapor separation section 13 comprises a casing 50 Xedly attached to the casing 30 'and formed with an internal cavity 51, an inlet port 52 for receiving the inlet conduit 46, a barrier portion 53, an outlet opening 54, and a vapor relief port 55. The fuel inlet conduit 46 is connected to the lowermost portion of a fuel supply tank 56, and the outlet opening 54 is connected to the pumping chamber 31b of the pumping section 12 through the inlet valve 45. It is contemplated that the pump 10 may also be mounted within the tank 56.

The vapor relief port 55 opens into a fluted chamber 57 which is connected through a conduit 58 to an uppermost portion of the fuel supply tank 56. A buoyant valve plug or float 59 is disposed within the chamber 57 and is adapted to seal against the port 55. The float 59 is centered within the chamber 57 by flutes 60 formed in the side wall and is prevented from blocking the outlet conduit 58 by tangs 6l formed on an end of the conduit 58. The float 59 is adapted to seal against the port 55 whenever the fuel level in the tank is insufficient to raise the the float 59 away from the port 55, for instance if the vehicle is on an incline with a small amount -of gasoline in the tank. The float 59 in a port-blocking position prevents the drawing of air or vapor into chamber 51 from the tank 56 through the conduit 5S.

In operation, fuel from the tank 56 is normally supplied by gravity feed through the inlet conduit 46 to the cavity 51. The motor 14 is energized so as to set the shaft 15 and eccentric shaft 16 into rotation for reciprocating the -pumping plunger 32. During a portion of its stroke, fuel is sucked into the chamber 31b through the inlet valve 45.

As the eccentric shaft 16 rotates further, the plunger 32 is forced to the right compressing the fuel within the chamber 311:. The inlet valve 45 is closed and the fuel Within the chamber 31h is forced through the discharge valve 42 and channel 41 into the chamber 31a. During the next portion of the pumping stroke, the spring 36 forces the plunger 32 to the left, closing the valve 42 and forcing the fuel from the chamber31a through the outlet port 47.

It should be noted that the pumping section 12 is doubleacting inasmuch as fuel is sucked into the chamber 3119 through the inlet valve 45 at the same time that fuel is being forced out of the chamber 31a through the port 47 when the plunger 32 moves to the left. Similarly, during the compression stroke while fuel within the chamber 31b is compressed, half of the fuel forced from the chamber 31b fills the chamber 31a and the other half is forced through theoutlet port 47, because of the difference in cross sectional area between the head 39 and the body portion of the pumping plunger.

The outlet pressure of the fuel supplied through the port 47 is determined substantially by the strength of the spring 36, and the volume of fuel delivered depends upon the longitudinal displacement during each stroke of the pumping plunger 32.

For proper performance of the pumping section 12, it is important that vapor be eliminated from the fuel supplied to the pumping charnber 31b. For this purpose, the barrier portion 53 acts as a baille to separate the bubbles formed by vapor within the fuel from the heavier liquid portion of the fuel. Normally, the pump is to be operated in the position shown, and the vapor bubbles travel through the port 55, past the float 59, and through the conduit S and back to the tank 56. The liquid portion .of the fuel passes through the inlet valve 45 into the chamber 31b. As previously described, the valve plug 59 acts to seal off the port 55 so as to prevent the entry of air or vapor from the conduit 58 into the inlet valve 45 whenever there is insuicient fuel in the tank 56 to oat the plug 59 or when the car happens to be on an incline with a near empty tank. It is important that the vapor be eliminated at a point immediately adjacent to the fluid inlet port to the pumping chamber so as to prevent the reforming of vapor bubbles in the Huid prior to entering the pump.

The stroke of the pumping plunger 32 is variable, as previously described, in accordance with the fuel demand by the internal fuel combustion engine being supplied. The spring 36 establishes the nominal operating pressure of the output fluid, and the force exerted by the spring is balanced by the output pressure acting against the dilferential area of the head 39 and body portion of the plunger 32. During normal operation, the return stroke o-f the pumping plunger 32 is, therefore, limited by the output pressure. The limited return stroke of the plunger 32 results in intermittent contact between the drive sleeve 23 and the cap 35 attached to the end of the plunger 32. This intermittent contact has been found to produce undesirable noise.

The intensity of this noise has been minimized by the following means: (a) the provision of the rubber cap 35 softens the actual contact between the driving sleeve 23 and the plunger 32; (b) the flexible coupling 17 reduces the impact between the sleeve 23 and cap 35 by permitting torsional flexing between the eccentric shaft 16 and output shaft 15 thereby minimizing the effective inertia of the motor armature and extending the time lag in reversing the direction of the pumping plunger 32; and (c) the spring 38 tends to force the sleeve 23 and eccentric shaft 16 toward the left, as shown, at all times. The action of the spring 38 counteracts the unbalanced forces produced by the eccentric shaft 16 and the eccentrically mounted sleeve 23, thereby substantially preventing radial motion or backlash of the eccentric shaft 16 and sleeve 23 due to clearance within the bearings 19 and 24 at the time of contact.

Referring to FIG. 4, there is illustrated a modification of the pump of FIG. 2, incorporating a vacuum pump 70 that is adapted to be driven by the motor 14.

The vacuum pump 70 comprises a casing 71 attached to the casing 18 and formed with a longitudinal cylindrical bore 72 and a piston 73 slidably disposed Within the bore 72. The bore 72 is adapted to be sealed at one end by a flapper-type inlet valve 74 which is held in place by an end cap 75. The cap 75 is threaded on the casing 71 and formed with a neck portion 76 and a longitudinnal cylindrical bore 77. The neck portion 76 is adapted to receive a flexible tube or conduit connected to a vacuum reference control for the fuel injection system with which the pump 10 is intended toI be used.

The piston 73 is adapted to be reciprocated within the bore 72 by means of a connecting rod 78 attached to the sleeve 23. The piston 73 is formed with an annular groove 79 which carries a unidirectional sealing ring 80. The casing 71 is formed With an annular groove 81 surrounding the piston 73 and a radial air-discharge port 82.

In operation, the vacuum pump 70 functions as follows: The motor 14 is energized setting the eccentric shaft 16 and sleeve 23 into rotation. The eccentric shaft 16 causes the piston 73 to reciprocate within the bore 72. During a downstroke, that is when the piston 73 moves to the iight, as shown, air is sucked into the bore 72 through the inlet Valve 74. During a compression, that is when the piston 73 moves to the left, as shown, the valve 74 closes and air within the bore 72 is compressed. A portion -of the air compressed within the bore 72 is forced past the sealing ring 80y and out through the discharge port 82. The sealing ring 80 is in the form of an inverted V in cross section and is unidirectional in operation, that is, it permits the passage of air during the compression stroke but prevents the backward passage of air during the suction stroke.

For the embodiment shown in FIG. 4, the spring 38 can be eliminated. Once a partial vacuum is established within the bore 77, there will be a net total force acting against the piston 73 tending to move it to the left. The net tota'. force so established acts to eliminate radial motion or backlash due to clearance within the bearings 19 and 24. The vacuum pump 70, therefore, performs the same functions as t-he spring 38 in partially eliminating noise due to backlash Within the bearings.

There has been provided by this invention, an improved fuel supply pump adapted to supply a variable volume output at a substantially constant pressure and that is of a practicable size and cost for automotive use.

The pump of the present invention effectively eliminates noise `due to variable stroke of the plunger.

It is to be understood that the invention is not to be limited to the specific constructions and arrangements `shown and described, except only insofar as the claims may be Iso limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

We claim:

1. In a fluid pump having a variable stroke pumping plunger and driving means including a rotatable output shaft for reciprocating the plunger, the combination of a casing, an eccentric or crank shaft journaled within said casing at right an-gles to the pumping plunger, first resilient means interconnecting said crank shaft With the output shaft of the driving means, a sleeve rotatably journaled on an end of said crank shaft, second resilient means mounted in said casing and engaging said sleeve and effective to force said sleeve and crank shaft away from the plunger and thereby minimize noise due to bearing clearances, and third resilient means mounted on the end of the pumping plunge-r and adapted to be contacted by said sleeve for moving the plunger, said three resilient means collectively being effective to minimize noise due to intermittent contact between said sleeve and the pumping plunger.

2. A uid pump as claimed in claim 1 wherein said resilient means comprises a generally Ushaped coil spring engaging said sleeve.

3. In a fluid pump having a variable stroke pumping plunger and driving means including a rotatable output shaft for reciprocating the plunger, the combination of a casing, a crank shaft rotatably disposed within said casing, first bearing means for supporting said crank shaft within said casing, a sleeve rotatably disposed on an end of said crank shaft, second bearing means for rotatably supporting said sleeve on said crank shaft, rst re'silient means engaging said sleeve to force said sleeve and crankshaft away from the plunger and thereby minimize noise due to radial clearances within said lirst and second bearing means, second -resilient means mounted on an end of the pumping plunger and adapted to be contacted intermittently by said sleeve for moving the plunger, said two resilient means being effective to minimize noise due to -intermittent contact between said sleeve and said pumping plunger.

References Cited by the Examiner UNITED STATES PATENTS Walker 64-13 MacDonald 64-13 Davey 64-13 Babitch 103-38 Hurst 10S-38 Hoier 103-38 Horton 10S-213 Dyer 74-50 Anderson 103-38 Nevin et al 103-38 Edelman et al 103-162 Pierce 103-148 SAMUEL LEVINE, Primary Examiner.

DONLEY J. STOCKING, Examiner.

20 W. L. FREEH, Assistant Examiner. 

1. IN A FLUID PUMP HAVING A VARIABLE STROKE PUMPING PLUNGER AND DRIVING MEANS INCLUDING A ROTATABLE OUTPUT SHAFT FOR RECIPROCATING THE PLUNGER, THE COMBINATION OF A CASING, AN ECCENTRIC OR CRANK SHAFT JOURNALED WITHIN SAID CASING AT RIGHT ANGLES TO THE PUMPING PLUNGER, FIRST RESILIENT MEANS INTERCONNECTING SAID CRANK SHAFT WITH THE OUTPUT SHAFT OF THE DRIVING MEANS, A SLEEVE ROTATABLY JOURNALED ON AN END OF SAID CRANK SHAFT, SECOND RESILIENT MEANS MOUNTED IN SAID CASING AND ENGAGING SAID SLEEVE AND EFFECTIVE TO FORCE SAID SLEEVE AND CRANK SHAFT AWAY FROM THE PLUNGER AND THEREBY MINIMIZE NOISE DUE TO BEARING CLEARANCES, AND THIRD RESILIENT MEANS MOUNTED ON THE END OF THE PUMPING PLUNGER AND ADAPTED TO BE CONTACTED BY SAID SLEEVE FOR MOVING THE PLUNGER, SAID THREE RESILIENT MEANS COLLECTIVELY BEING EFFECTIVE TO MINIMIZE NOISE DUE TO INTERMITTENT CONTACT BETWEEN SAID SLEEVE AND THE PUMPING PLUNGER. 